Typically, lithium-ion batteries (“LiBs”) include a current collector, cathode, membrane, electrolyte, anode, and a second current collector. The use of the membrane in a conventional LiB makes conventional LiBs unsuitable for some applications or uses. One known problem with the use of a membrane in LiBs is that above 140-160° C., the membrane melts, and the melting can short-circuit the cell. In addition to the risk of melting the membrane, ambient temperatures outside the LiB operating temperature range can decrease a conventional LiBs' performance, accelerating their aging process, and exceeding the safety properties of cell materials. External thermal management systems must therefore be used in some systems that include conventional LiBs.
Additionally, because the membrane between the electrodes in a conventional LiB is separate from the electrodes, the membrane can suffer viscoelastic creep with repeated cycles. A membrane commonly used in LiBs is an insulative polypropylene-type polymer that is stretched until small pores are formed. The membrane's pores can shrink over time, which increases the resistance to the flow of ions across the membrane.
Another problem with conventional LiBs that include a membrane is that the membrane can be difficult to place between the electrodes, and when the outside battery casing is twisted over the battery components during assembly, damage can be done to the membrane. Also, typically, LiBs are made with a flammable electrolyte, which poses a safety risk because it can cause the LiB to explode.
There exists a need for lithium-ion battery technology that allows for increased thermal stability such that the LiBs have a wider range of temperatures in which they can operate. Specifically, a need exists for LiBs that can operate at higher temperatures than conventional LiBs operate. Increased thermal stability could eliminate the need for external thermal management systems for LiB battery packs. Eliminating the need for the external thermal management system would allow for more economical and streamlined battery packs. There is also a need for LiBs that have increased structural stability to allow the batteries to withstand compression forces and other such forces.